It is often desirable to thin a timbered area by felling younger and smaller trees, for example those having up to a 6 inch diameter trunk, or by removing underbrush or logging slash or any other undesirable forest residue or vegetation. Typically the wood should be broken up into small pieces or chips to foster rapid decomposition and to minimize fire danger. Although a number of different types of machines have been used for this purpose, one having a reduction head mounted on a horizontal shaft with rows of swinging blades appears to be advantageous because it is capable of cutting closer to the ground, and is safer in that it has less tendency to throw cut material in all directions. Moreover, the reduction head is closely coupled to the vehicle to provide good operator visibility.
A typical machine of this type has a drum or reel that includes a plurality of angularly spaced transverse shafts or bars on its outer periphery. Each shaft mounts a number of free-swinging, U-shaped cutter elements that are spaced apart and have sharpened cutting edges on the lower side thereof. The reel is mounted on the front of a wheeled or tracked vehicle and is rotated at high speed by a hydraulic motor. Each cutter element blade strikes the target and then is pushed back somewhat, but then swings forward to the correct position for the next impact during the next revolution of the reel. So long as the blades on the cutter elements remain sharp, the small trees, brush or slash is reduced to small chips in short order.
One inefficiency in prior cutter designs is that the location of its center of mass with respect to its center of rotation has not been optimized to give the best impact force on each revolution. This reduces cutting efficiency, and increases vibration. Another shortcoming of prior cutter design lies in the shape of the cutting edge. Prior edges have been straight, which reduces the penetration of the blade into the wood on each impact, and thus increases the time required to cut through a given thickness. These cutters also wear out rather rapidly and cannot be resharpened because the worn metal face is well above to bottom surfaces of the sides thereof which block engagement of a resharpened edge on the front.
An object of the present invention is to provide a new and improved cutter blade for a rotating reduction head that obviates the foregoing disadvantage of prior devices.
Another object of the present invention is to provide a new and improved free-swinging cutter for a rotating reduction head that is designed to have greater impact force on each engagement with the wood.
Another object of the present invention is to provide a new and improved cutter of the type described having its cutting edge shaped and arranged to obtain greater penetration on each impact.
Yet another object of the present invention is to provide a new and improved cutter of the type described having a substantially increased wear life compared to prior devices.